Arsenic levels in soil of a town polluted 35 years ago (Nakajo, Japan)

Abstract

Endemic arsenic poisoning occurred in Nakajo Town, Prefecture, Japan, in 1950. Of 454 residents who took medical examinations , 93 residents (20.5%) had symptoms of chronic arsenicism. Most of the patients within 500m of the south-west side of the factory. The authors were interested in the current environmental arsenic contamination in Nakajo in terms of assessing the effects of arsenic on human health. To examine the geographical distribution of arsenic, soil was sampled on the assumption that soil is the most directly polluted environmental medium by the contaminated well water. In fact, well water was used for agriculture and livestock husbandry in the town. Once soil is contaminated with toxic substances, such substances are not easily lost or decomposed and remain in soil for a long period of time. Well water is an ideal material for environmental arsenic determination, but wells are now closed. Sampling of agricultural products and human blood were rejected by the town office for fear that they would cause unnecessary public concern. This study was conducted as a part of investigations into health effects of the arsenic poisoning caused 35 years ago by waste water contaminated with arsenic in Nakajo. The purpose of this work is more » to determine the current soil arsenic levels and assess the possible influence of arsenic on human health. 16 refs., 1 fig., 5 tabs. « less